When Frodo and Sam were in Shelobs lair, Sam suddenly knew the right words to say,words he never heared before, to activate the Phial. Now I wonder was it through Galadriel that he knew the words and that it shined so brightly or was it due to Vardas help.

Same with the change of weather, when Sam wished for water and daylight, after some time it happens. Is Galadriel responsable for that? Has she even the power to do so or was that also Varda?